Microstructure and Properties of Novel Fluorescent Pyrene Functionalized PANI/P(VDF-HFP) Blend Veer Pal Singh, 1 Ramasubbu Ramani, 1 Vijay Pal, 1 Asit Prakash, 2 Sarfaraz Alam 1 1 Polymer Science Division, D.M.S.R.D.E., G.T. Road, Kanpur 208 013, India 2 Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208 016, India Correspondence to: S. Alam (E - mail: sarfarazkazmi@yahoo.com) ABSTRACT: We herein report the preparation and properties of the first polymer blend using pyrene functionalized polyaniline (pf- PANI). The pf-PANI has been synthesized and its blend has been prepared with the copolymer of vinylidene fluoride and hexafluoro- propylene P(VDF-HFP). The FTIR results reveal intermolecular interaction between the polar amide group of pf-PANI and the polar- ized CH 2 group of P(VDF-HFP). The crystalline phase of PVDF of the copolymer revealed a transformation from a to b crystalline form after blending with pf-PANI, as found from FTIR and XRD measurements. The calorimetric measurements together with DMA results revealed the blend is partially miscible. The SEM measurements showed that the pf-PANI has been dispersed uniformly in the P(VDF-HFP) matrix. The solution photoluminescence spectrum of the pf-PANI exhibited emission in the purple–blue region and is slightly red shifted for the blend. The possible applications of this flexible fluorescent pf-PANI/P(VDF-HFP) has been suggested. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40163. KEYWORDS: pyrene functionalization; polyaniline; poly(vinylidene fluoride-co-hexafluoro propylene); polymer blend; X-ray diffraction Received 7 July 2013; accepted 1 November 2013 DOI: 10.1002/app.40163 INTRODUCTION Fluoropolymers such as poly(vinylidene fluoride) (PVDF) and its copolymers are technologically important thermoplastics because of their availability in different crystalline forms. 1 The incorporation of amorphous phase of hexafluoropropylene (HFP) into the main constituent vinylidene fluoride (VDF) blocks has been reported to modify some of the properties of the homopolymer. Particularly, the degree of crystallinity of P(VDF-HFP) is significantly reduced in comparison with PVDF, while the flexibility and solubility for organic solvents are enor- mously increased. 1,2 The amorphous HFP domains can trap more liquid electrolytes and the crystalline regions (of VDF) can help to maintain mechanical integrity of the film. On account of this merit, P(VDF-HFP) has received special atten- tion as one of the promising host polymers for polymer electro- lytes. 2–4 In addition, the dielectric permittivity of P(VDF-HFP) is also high as compared with other conventional polymers. 4 Amongst conductive polymers, polyaniline (PANI) has received special attention since it possess excellent conductivity. 5 How- ever, the processibility of PANI has been a crucial factor in making use of its interesting electrical and electrochemical properties in real applications since it is insoluble in common organic solvents and is unstable at melt processing tempera- tures. 6,7 In addition, the molecular weight of PANI is relatively poor in comparison with other conventional polymers. 6 Thus, blending PANI with other conventional polymers, could lead to blend with excellent mechanical properties and high processibil- ity of the conventional polymers together with the electrical conductivity of PANI. This could increase the technological potential and the commercial viability of PANI. 8,9 Keeping this aspect in view, successful blends have been prepared in the past with conventional polymers like poly(vinyl acetate), 10 poly(- methyl methacrylate) (PMMA), 11 polystyrene, 12 polycarbon- ate, 13 poly(ethylene terephthalate) 14 as well as with copolymer poly(ethylene-co-vinyl acetate) 8 thus leading to materials of high mechanical strength and with good electrical conductivity. But, previous attempts to prepare blends of PANI with PVDF by mixing them in common solvent turned out to be unsuccess- ful (as PANI precipitated forming a two-phase system). 6 The miscibility between PANI and PVDF has been suggested to improve by adding poly(vinyl chloride) 15 which however resulted to low mechanical strength and conductivity. But, the derivatives of PANI like poly(o-methoxyaniline) and poly(o- ethoxyaniline) and PVDF are reported to be miscible because of the presence of polar groups in these PANI derivatives. 6,16 An alternate method to obtain PANI/PVDF blends has been reported in which the oxidative polymerization of aniline is per- formed in solution of PVDF using P-toluene sulfonic acid (p- V C 2013 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2014, DOI: 10.1002/APP.40163 40163 (1 of 11)